U.S. patent number 9,741,585 [Application Number 15/096,381] was granted by the patent office on 2017-08-22 for reactive radical treatment for polymer removal and workpiece cleaning.
This patent grant is currently assigned to Taiwan Semiconductor Manufacturing Co., Ltd.. The grantee listed for this patent is Taiwan Semiconductor Manufacturing Co., Ltd.. Invention is credited to Chung-Chieh Lee, Horng-Huei Tseng, Chi-Ming Yang.
United States Patent |
9,741,585 |
Lee , et al. |
August 22, 2017 |
Reactive radical treatment for polymer removal and workpiece
cleaning
Abstract
A method for removing polymer is provided. An aqueous solution
is applied to a semiconductor workpiece with polymer arranged
thereon. The aqueous solution comprises an energy receiver
configured to generate reactive radicals in response to energy.
Energy is applied to the aqueous solution to generate the reactive
radicals in the aqueous solution and to remove the polymer. A
process tool for generating the reactive radicals is also
provided.
Inventors: |
Lee; Chung-Chieh (Taipei,
TW), Tseng; Horng-Huei (Hsin Chu, TW),
Yang; Chi-Ming (Hsinchu, TW) |
Applicant: |
Name |
City |
State |
Country |
Type |
Taiwan Semiconductor Manufacturing Co., Ltd. |
Hsin-Chu |
N/A |
TW |
|
|
Assignee: |
Taiwan Semiconductor Manufacturing
Co., Ltd. (Hsin-Chu, TW)
|
Family
ID: |
59581516 |
Appl.
No.: |
15/096,381 |
Filed: |
April 12, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L
21/3065 (20130101); H01L 21/31155 (20130101); H01L
29/66795 (20130101); H01L 21/31133 (20130101); H01L
21/0206 (20130101); H01L 21/02057 (20130101); H01J
37/32009 (20130101); H01J 2237/334 (20130101) |
Current International
Class: |
H01L
21/302 (20060101); H01L 21/311 (20060101); H01J
37/32 (20060101); H01L 21/3065 (20060101); H01L
21/3115 (20060101); H01L 21/02 (20060101) |
Field of
Search: |
;438/706,708,709,714,725,745,762 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Reinhart, et al. "Handbook of Cleaning for Semiconductor
Manufacturing: Fundamentals and Applications." pp. 71-94. ISBN:
978-0-470-62595-8. Jan. 2011. cited by applicant .
Reinhart, et al. "Handbook of Cleaning for Semiconductor
Manufacturing: Fundamentals and Applications." pp. 211-214. ISBN:
978-0-470-62595-8. Jan. 2011. cited by applicant.
|
Primary Examiner: Vinh; Lan
Attorney, Agent or Firm: Eschweiler & Potashnik, LLC
Claims
What is claimed is:
1. A method for removing polymer, the method comprising: performing
a first etch selectively into a semiconductor workpiece to form a
fin protruding upward from a base of the semiconductor workpiece,
wherein the first etch results in a polymer by-product layer lining
the fin; applying an aqueous solution to the semiconductor
workpiece with the polymer by-product layer arranged thereon,
wherein the aqueous solution comprises an energy receiver
configured to generate reactive radicals in response to energy;
applying energy to the aqueous solution to generate the reactive
radicals in the aqueous solution and to remove the polymer
by-product layer; forming a photoresist layer masking a gate region
of the fin; implanting ions into regions of the fin unmasked by the
photoresist layer to define a pair of source/drain regions in the
fin, wherein implanting the ions results in an additional polymer
by-product layer on the photoresist layer; applying a fluid with
reactive radicals to the additional polymer by-product layer to
remove the additional polymer by-product layer; and after removing
the additional polymer by-product layer, forming a gate electrode
straddling the gate region of the fin.
2. The method according to claim 1, wherein the reactive radicals
in the aqueous solution are hydroxyl (OH) radicals.
3. The method according to claim 1, wherein the reactive radicals
in the aqueous solution are radicals with a lifetime less than
about 1 second and an oxidation potential greater than about 1.8
volts.
4. The method according to claim 1, further comprising: applying
the aqueous solution to the semiconductor workpiece with the
aqueous solution at a temperature less than 100 degrees
Celsius.
5. The method according to claim 1, further comprising: applying
the energy to the aqueous solution to generate the reactive
radicals with a concentration greater than one part per million
(ppm) in the aqueous solution.
6. The method according to claim 1, further comprising: generating
the aqueous solution with ozonated deionized water as the energy
receiver.
7. The method according to claim 1, further comprising: generating
the aqueous solution with hydrogen peroxide as the energy
receiver.
8. The method according to claim 1, further comprising: generating
the aqueous solution with a concentration of energy receiver that
is between 1 part per million (ppm) and 30 percent by mass (wt
%).
9. The method according to claim 1, further comprising: applying
the energy to the energy receiver with ultraviolet radiation, sound
waves, or infrared radiation.
10. The method according to claim 1, wherein the first etch is a
dry etch, and wherein the polymer by-product layer comprises
process gas residue from the dry etch.
11. The method according to claim 1, wherein the first etch is a
dry etch, and wherein the polymer by-product layer comprises
fluorocarbon polymer.
12. The method according to claim 1, further comprising: performing
a semiconductor manufacturing process to form the polymer
by-product layer on a silicon, germanium, or group III-V
substrate.
13. The method according to claim 1, further comprising: forming a
patterned hard mask layer on the semiconductor workpiece, wherein
the first etch is performed with the patterned hard mask layer in
place and results in the polymer by-product layer further lining
the patterned hard mask layer; after removing the polymer
by-product layer, performing a second etch into the patterned hard
mask layer to remove the patterned hard mask layer from the
semiconductor workpiece; forming a dielectric layer covering the
semiconductor workpiece; and performing a third etch into the
dielectric layer to recess a top surface of the dielectric layer to
below a top surface of the fin.
14. A method for removing polymer, the method comprising:
performing a first etch into a semiconductor workpiece, wherein the
first etch results in a polymer by-product layer lining the
semiconductor workpiece; generating a fluid with hydroxyl radicals
from ozonated deionized water or hydrogen peroxide; applying the
fluid to the semiconductor workpiece to remove the polymer
by-product layer from the semiconductor workpiece; forming a
photoresist layer masking a gate region of the semiconductor
workpiece; implanting ions into regions of the semiconductor
workpiece unmasked by the photoresist layer to define a pair of
source/drain regions, wherein implanting the ions results in an
additional polymer by-product layer on the photoresist layer;
applying an additional fluid with hydroxyl radicals to the
additional polymer by-product layer to remove the additional
polymer by-product layer; and after removing the additional polymer
by-product layer, forming a gate electrode covering the gate region
of the semiconductor workpiece.
15. The method according to claim 14, wherein the fluid is applied
to the semiconductor workpiece at a temperature less than about 100
degrees Celsius and with a concentration of hydroxyl radicals
greater than about 1 part per million.
16. The method according to claim 14, wherein applying the fluid to
the semiconductor workpiece comprises increasing solubility or
wettability of the polymer by-product layer.
17. The method according to claim 14, further comprising: forming a
patterned hard mask layer on the semiconductor workpiece, wherein
the first etch is performed with the patterned hard mask layer in
place and results in the polymer by-product layer further lining
the hard mask layer, and wherein the first etch is performed to
form a fin protruding upward from a base of the semiconductor
workpiece; after removing the polymer by-product layer, performing
a second etch into the patterned hard mask layer to remove the
patterned hard mask layer from the semiconductor workpiece; forming
a dielectric layer covering the semiconductor workpiece; and
performing a third etch into the dielectric layer to recess a top
surface of the dielectric layer to below a top surface of the fin;
wherein the gate region is in the fin, wherein the source/drain
regions are formed in the fin, and wherein the gate electrode is
formed straddling the fin.
18. The method according to claim 17, wherein the additional fluid
is applied to the additional polymer by-product layer at a
temperature less than about 100 degrees Celsius and with a
concentration of hydroxyl radicals greater than about 1 part per
million, and wherein applying the additional fluid comprises
increasing solubility or wettability of the additional polymer
by-product layer.
19. A method for manufacturing an integrated circuit, the method
comprising: forming a patterned hard mask layer on a semiconductor
substrate; performing a first etch into the semiconductor substrate
to form a fin protruding upward from a base of the semiconductor
substrate, wherein the first etch is performed with the patterned
hard mask layer in place, and wherein the first etch results in a
polymer by-product layer lining the fin and the patterned hard mask
layer; applying a fluid with hydroxyl radicals to the polymer
by-product layer to remove the polymer by-product layer; performing
a second etch into the patterned hard mask layer to remove the
patterned hard mask layer from the semiconductor substrate; forming
a dielectric layer covering the semiconductor substrate; performing
a third etch into the dielectric layer to recess a top surface of
the dielectric layer to below a top surface of the fin; forming a
photoresist layer masking a gate region of the fin; implanting ions
into regions of the fin unmasked by the photoresist layer to define
a pair of source/drain regions in the fin, wherein implanting the
ions results in an additional polymer by-product layer on the
photoresist layer; applying another fluid with hydroxyl radicals to
the additional polymer by-product layer to remove the additional
polymer by-product layer; and after removing the additional polymer
by-product layer, forming a gate electrode straddling the gate
region of the fin.
20. The method according to claim 19, wherein the other fluid is
applied to the additional polymer by-product layer at a temperature
less than about 100 degrees Celsius and with a concentration of
hydroxyl radicals greater than about 1 part per million, and
wherein applying the other fluid comprises increasing solubility or
wettability of the additional polymer by-product layer.
Description
BACKGROUND
During the manufacture of integrated circuits (ICs), multi-step
sequences of semiconductor manufacturing processes are performed to
gradually form electronic circuits on semiconductor workpieces. The
semiconductor manufacturing processes may include, for example, ion
implantation, plasma etching, and polymer cleaning. Polymer
cleaning is a process for removing polymer used by or otherwise
resulting from other semiconductor manufacturing processes, such
as, for example, ion implantation and plasma etching. The polymer
may include, for example, ion implanted photoresist and/or
fluorocarbon polymer. One type of polymer cleaning process commonly
used to remove polymer during front-end-of-line (FEOL)
manufacturing is a sulfuric acid-hydrogen peroxide mixture (SPM)
cleaning process.
BRIEF DESCRIPTION OF THE DRAWINGS
Aspects of the present disclosure are best understood from the
following detailed description when read with the accompanying
figures. It is noted that, in accordance with the standard practice
in the industry, various features are not drawn to scale. In fact,
the dimensions of the various features may be arbitrarily increased
or reduced for clarity of discussion.
FIGS. 1A-1C illustrate a series of cross-sectional views of some
embodiments of a method for removing polymer using reactive
radicals.
FIG. 2 illustrates a flowchart of some embodiments of the method of
FIGS. 1A-1C.
FIG. 3 illustrates a cross-sectional view of some embodiments of a
process tool for generating steam with reactive radicals.
FIGS. 4A and 4B illustrate cross-sectional views of some
embodiments of a process tool for generating an aqueous solution
with reactive radicals.
FIGS. 5-22 illustrate a series of cross-sectional and perspective
views of some embodiments of a method for manufacturing a fin
field-effect transistor (finFET) using reactive radicals for
polymer cleaning.
FIG. 23 illustrates a flowchart of some embodiments of the method
of FIGS. 5-22.
DETAILED DESCRIPTION
The present disclosure provides many different embodiments, or
examples, for implementing different features of this disclosure.
Specific examples of components and arrangements are described
below to simplify the present disclosure. These are, of course,
merely examples and are not intended to be limiting. For example,
the formation of a first feature over or on a second feature in the
description that follows may include embodiments in which the first
and second features are formed in direct contact, and may also
include embodiments in which additional features may be formed
between the first and second features, such that the first and
second features may not be in direct contact. In addition, the
present disclosure may repeat reference numerals and/or letters in
the various examples. This repetition is for the purpose of
simplicity and clarity and does not in itself dictate a
relationship between the various embodiments and/or configurations
discussed.
Further, spatially relative terms, such as "beneath," "below,"
"lower," "above," "upper" and the like, may be used herein for ease
of description to describe one element or feature's relationship to
another element(s) or feature(s) as illustrated in the figures. The
spatially relative terms are intended to encompass different
orientations of the device in use or operation in addition to the
orientation depicted in the figures. The apparatus may be otherwise
oriented (rotated 90 degrees or at other orientations) and the
spatially relative descriptors used herein may likewise be
interpreted accordingly.
Some sulfuric acid-hydrogen peroxide mixture (SPM) cleaning
processes for removing polymer from a workpiece comprise applying a
mixture of sulfuric acid solution and hydrogen peroxide solution to
the polymer at high temperatures and with high concentrations of
sulfuric acid. The high temperatures may, for example, exceed 100
degrees Celsius, and/or the high concentrations of sulfuric acid
may, for example, exceed 85 percent by mass (wt %) in the sulfuric
acid solution. The high temperatures and the high concentrations of
sulfuric acid dissolve or detach the polymer, and the sulfuric acid
solution and the hydrogen peroxide solution react to produce Caro's
acid (e.g., peroxymonosulfuric acid). The Caro's acid and/or the
hydrogen peroxide then react with the dissolved or detached polymer
to oxidize the the polymer and to convert the polymer to water and
carbon dioxide.
A challenge with the SPM cleaning processes is high thermal stress.
Certain polymers, such as ion-implanted photoresist, induce stress
on features under manufacture, such as fins of fin field-effect
transistors (finFETs), and the high temperatures may exacerbate the
stress. At small feature sizes, such as less than about 7
nanometers, features are weak and the high thermal stress may lead
to a high likelihood of peeling and/or collapse. Further, to the
extent that temperatures of the SPM cleaning processes are reduced,
the solubility of the polymer and hence the cleaning efficiency
reduces. Another challenge with the SPM cleaning processes is
solubility and/or wettability. Certain polymers, such as
ion-implanted photoresist and fluorocarbon polymer, have poor
solubility and/or wettability in the mixture, such that cleaning
efficiency may be low. Yet another challenge with the SPM cleaning
processes is slow oxidation of the polymer, since Caro's acid is
the dominant oxidant in the mixture.
The present application is directed towards a method for removing
polymer using reactive radicals, as well as a process tool for
performing the method. In some embodiments, an aqueous solution is
applied to a semiconductor workpiece with polymer arranged thereon.
The aqueous solution comprises an energy receiver configured to
generate reactive radicals in response to energy. Energy is applied
to the aqueous solution to generate the reactive radicals in the
aqueous solution and to remove the polymer. Where the reactive
radicals are hydroxyl radicals, the polymer may advantageously be
removed at low temperatures, such as less than about 100 degrees
Celsius. As such, thermal stress on the semiconductor workpiece is
minimal, and the likelihood of feature collapse or peeling is
minimal. Further, high concentrations of the hydroxyl radicals,
such as greater than 1 part per million (ppm), advantageously
increase solubility and/or wettability to the aqueous solution
and/or other aqueous solutions, thereby promoting high cleaning
efficiency.
With reference to FIGS. 1A-1C, a series of cross-sectional views
100A-100C illustrate some embodiments of a method for removing
polymer using reactive radicals.
As illustrated by the cross-sectional view 100A of FIG. 1A, one or
more semiconductor manufacturing processes are performed to form
polymer 102 over a semiconductor workpiece 104. The polymer 102 may
be, for example, ion-implanted photoresist, photoresist without ion
implants, fluorocarbon polymer, and dry-etch-gas polymer. The
semiconductor workpiece 104 comprises a semiconductor substrate
and, in some embodiments, one or more additional layers and/or
structures stacked thereover. The semiconductor substrate may be,
for example, a bulk silicon substrate (e.g., of monocrystalline
silicon), a germanium substrate, or a group III-V substrate.
In embodiments where the polymer 102 is photoresist with or without
ion implants, the semiconductor manufacturing process(es) may, for
example, comprise spin coating or otherwise depositing the polymer
102 and/or ion implantation into the polymer 102. In embodiments
where the polymer 102 is fluorocarbon polymer, the semiconductor
manufacturing process(es) may, for example, comprise a dry etch
using process gases with carbon and fluoride, such as carbon
tetrafluoride. In embodiments where the polymer 102 is dry-etch-gas
polymer, the semiconductor manufacturing process(es) may, for
example, comprise dry etching.
As illustrated by the cross-sectional view 100B of FIG. 1B, a fluid
106 comprising reactive radicals 108 is generated and applied to
the polymer 102. In some embodiments, the fluid 106 has a
concentration of reactive radicals greater than about 1 ppm, and/or
the fluid 106 is an aqueous solution or steam. Further, in some
embodiments where the fluid 106 is an aqueous solution, the fluid
106 has a temperature less than about 100 degrees Celsius, such as
between 30-90 degrees Celsius. For example, the fluid 106 may be an
aqueous solution with a temperature less than about 100 degrees
Celsius, and/or a concentration of reactive radicals greater than
about 1 ppm, at the surface of the polymer 102. In alternative
embodiments, stable radicals, such as TEMPO, may be employed in
place of the reactive radicals 108.
The reactive radicals 108 are highly reactive, oxidative,
hydrophilic, or a combination the foregoing. For example, the
reactive radicals 108 may be hydroxyl (OH) radicals. As another
example, the reactive radicals 108 may be radicals that have a
lifetime less than about 1 second and that have an oxidation
potential greater than about 1.8 volts. The reactive radicals 108
react with and attach to the polymer 102 to modify the polymer 102
and to at least partially remove the polymer 102 from the
semiconductor workpiece 104. For example, the reactive radicals 108
may increase solubility of the polymer 102, increase wettability of
the polymer 102, reduce internal stress or hardness of the polymer
102, oxidize the polymer 102, or a combination of the foregoing.
The increase in solubility and/or wettability advantageously
facilitates high cleaning efficiency, and/or the reduction in
internal stress or hardness advantageously reduces the likelihood
of feature collapse and/or peeling. Further, the increased
solubility and/or oxidation advantageously facilitate removal of
the polymer 102.
In some embodiments, the fluid 106 is generated by applying energy
to an aqueous solution with an energy receiver dissolved therein.
The energy may be, for example, restricted so the aqueous solution
remains in liquid form, or may alternatively be, for example,
sufficient to gasify the aqueous solution. Further, the energy may,
for example, be applied by sound waves, infrared radiation, heat,
or ultraviolet (UV) radiation. The energy receiver is configured to
generate the reactive radicals 108 in response to the energy, and
is a chemical compound or molecule. For example, where the reactive
radicals 108 are hydroxyl radicals, the energy receiver may be, for
example, ozonated deionized water (e.g., DIO.sub.3) or hydrogen
peroxide (e.g., H.sub.2O.sub.2). Further, the energy receiver may,
for example, be dissolved in water (e.g., H.sub.2O), and/or may,
for example, have a concentration ranging from 1 ppm to 30 wt
%.
As illustrated by the cross-sectional view 100C of FIG. 1C, in some
embodiments, an additional polymer cleaning process is performed on
the semiconductor workpiece 104 to further remove the polymer 102
from the semiconductor workpiece 104. For example, a wet cleaning
solution or mixture 110 may be applied to the semiconductor
workpiece 104. The wet cleaning solution of mixture 110 may be, for
example, an SPM for front-end-of-line (FEOL) cleaning and/or an
organic solvent for back-end-of-line (BEOL) cleaning. As noted
above, the reactive radicals 108 may be sufficient to remove the
polymer 102. However, to the extent that the reactive radicals 108
are insufficient and the additional polymer cleaning process is
performed, the modification to the polymer 102 by the reactive
radicals 108 aids the additional polymer cleaning process in
removing the polymer 102. For example, cleaning efficiency may be
increased due to the increased wettability and/or the solubility of
the polymer 102. As another example, the likelihood of feature
collapse and/or peeling may be reduced due to the reduced stress or
hardness of the polymer 102.
With reference to FIG. 2, a flowchart 200 of some embodiments of
the method of FIGS. 1A-1C is provided.
At 202, a semiconductor manufacturing process is performed to form
polymer on a semiconductor workpiece. See, for example, FIG.
1A.
At 204, hydroxyl radicals are generated and applied to the
semiconductor workpiece to at least partially remove the polymer.
See, for example, FIG. 1B. In some embodiments, the process for
generating the hydroxyl radicals comprises applying at 204a a fluid
with an energy receiver to the semiconductor workpiece, where the
energy receiver is configured to generate the hydroxyl radicals in
response to energy. Further, in some embodiments, the process
comprises applying at 204b energy to the fluid to generate the
hydroxyl radicals in the fluid.
At 206, in some embodiments, an additional polymer cleaning process
is performed to further remove the polymer. See, for example, FIG.
1C.
While the method described by the flowchart 200 is illustrated and
described herein as a series of acts or events, it will be
appreciated that the illustrated ordering of such acts or events
are not to be interpreted in a limiting sense. For example, some
acts may occur in different orders and/or concurrently with other
acts or events apart from those illustrated and/or described
herein. Further, not all illustrated acts may be required to
implement one or more aspects or embodiments of the description
herein, and one or more of the acts depicted herein may be carried
out in one or more separate acts and/or phases.
With reference to FIG. 3, a cross-sectional view 300 of some
embodiments of a process tool for generating steam 106a with
reactive radicals 108 is provided. The process tool may, for
example, be employed during a polymer cleaning process and/or to
generate the fluid 106 of FIGS. 1A-1C and 2. As illustrated, a
housing 302 defines a process chamber 304 within which a workpiece
support 306 is arranged. In some embodiments, the process chamber
304 has a controlled atmosphere differing from an ambient
environment of the process tool. For example, the controlled
atmosphere may have a different pressure and/or temperature than
the ambient environment. The workpiece support 306 is configured to
support a semiconductor workpiece 104 and, in some embodiments, to
rotate the semiconductor workpiece 104 and/or to heat the
semiconductor workpiece 104.
The housing 302 comprises an inlet 308 and an outlet 310 that are
laterally spaced and respectively arranged on the top and the
bottom of the housing 302. The inlet 308 is connected to a steam
generator 312 and is configured to receive steam 106a with reactive
radicals 108 from the steam generator 312. The steam 106a may, for
example, have a temperature less than about 100 degrees Celsius.
Further, the reactive radicals 108 may, for example, have a
concentration greater than about 1 ppm in the steam 106a, and/or
may be, for example, hydroxyl radicals. In some embodiments, the
steam generator 312 is configured to generate the steam 106a by
gasifying or otherwise heating an aqueous solution with an energy
receiver arranged therein. The energy receiver is configured to
generate the reactive radicals 108 in response to energy and may
be, for example, received from a solution source 314. Where the
reactive radicals 108 are hydroxyl radicals, the aqueous solution
may be, for example, a hydrogen peroxide solution. The hydrogen
peroxide solution may, for example, have a concentration of
hydrogen peroxide between 1 ppm and 30 wt %. The outlet 310 is
connected to an exhaust pump 316 configured to receive the steam
106a from the process chamber 304 after it flows over the
semiconductor workpiece 104.
Advantageously, as the steam 106a and the reactive radicals 108
flow over the semiconductor workpiece 104, the reactive radicals
108 react with and attach to polymer (not shown) on the
semiconductor workpiece 104 to modify the polymer and to at least
partially remove the polymer from the semiconductor workpiece 104.
For example, the reactive radicals 108 may increase solubility,
increase wettability, reduce internal stress, or a combination of
the foregoing. Modification of the polymer 102 advantageously
facilitates high cleaning efficiency and/or reduces the likelihood
of feature collapse and/or peeling.
With reference to FIGS. 4A and 4B, cross-sectional views 400A, 400B
of some embodiments of a process tool for generating an aqueous
solution 106b with reactive radicals 108 is provided. The process
tool may, for example, be employed during a polymer cleaning
process and/or to generate the fluid 106 of FIGS. 1A-1C and 2.
As illustrated by the cross-sectional view 400A of FIG. 4A, a
chemical delivery device 402 is configured to deliver or otherwise
apply an aqueous solution 106b to a semiconductor workpiece 104
and, in some embodiments, to generate or otherwise mix the aqueous
solution. The aqueous solution 106b comprises an energy receiver
(e.g., a chemical compound) configured to generate reactive
radicals 108 in response to energy 404, and the energy receiver may
be or otherwise comprise, for example, ozonated deionized water or
hydrogen peroxide to generate the reactive radicals 108 as hydroxyl
radicals. In some embodiments, the chemical delivery device 402 is
configured to apply the aqueous solution 106b at a temperature less
than about 100 degrees Celsius, such as between about 30-90 degrees
Celsius, and/or is configured to apply the aqueous solution 106b
with a concentration of energy receiver that is between about 1 ppm
and 30 wt %. Further, in some embodiments, the chemical delivery
device 402 is configured to apply additional aqueous solutions to
the semiconductor workpiece 104, such as those used by an RCA
cleaning process.
An energy input device 406 is configured to apply the energy 404 to
the aqueous solution 106b, thereby generating the reactive radicals
108 in the aqueous solution 106b. In some embodiments, the energy
input device 406 applies the energy 404 with sufficient intensity
and/or duration to generate the reactive radicals 108 with a
concentration exceeding about 1 ppm in the aqueous solution 106b.
Further, in some embodiments, the energy input device 406 focuses
the energy 404 towards the semiconductor workpiece 104, so as to
generate the reactive radicals 108 at the semiconductor workpiece
104. The energy input device 406 may be, for example, an
ultraviolet lamp configured to apply the energy 404 by way of UV
radiation. Alternatively, the energy input device 406 may be, for
example, a sonic transducer configured to apply the energy 404 by
way of sound waves. Alternatively, the energy input device 406 may
be, for example, a heater configured to apply the energy 404 by
infrared radiation. In some embodiments, the heater is a resistive
heater, and/or is configured to apply the infrared radiation to the
aqueous solution 106b without accompanying UV radiation or sound
waves.
Advantageously, as the aqueous solution 106b and the reactive
radicals 108 react with and attach to polymer (not shown) on the
semiconductor workpiece 104 to modify the polymer and to at least
partially remove the polymer from the semiconductor workpiece 104.
For example, the reactive radicals 108 may increase solubility,
increase wettability, reduce internal stress, or a combination of
the foregoing. Modification of the polymer 102 advantageously
facilitates high cleaning efficiency and/or reduces the likelihood
of feature collapse and/or peeling.
As illustrated by the cross-sectional view 400B of FIG. 4B, a
housing 408 (partially shown) defines a cavity 410 within which a
workpiece support 306 is arranged. The workpiece support 306 is
configured to support a semiconductor workpiece 104 and, in some
embodiments, to rotate the semiconductor workpiece 104.
The energy input device 406 is arranged over the workpiece support
306, proximate an opening in the housing 408. Further, in some
embodiments, the energy input device 406 fully covers the workpiece
support 306. The energy input device 406 comprises a body 412
supporting a UV lamp 414 therein, and further comprises a conduit
416 extending through the body 412. The conduit 416 connects to the
chemical delivery device 402 and provides the chemical delivery
device 402 with a path for introducing the aqueous solution 106b to
the semiconductor workpiece 104. In some embodiments, the conduit
416 is arranged at an axis of rotation for the workpiece support
306, such that centrifugal force moves the aqueous solution 106b to
a periphery of the semiconductor workpiece 104.
With reference to FIGS. 5-22, a series of cross-sectional and
perspective views 500-2200 illustrate some embodiments of a method
for manufacturing a finFET using reactive radicals for polymer
cleaning. The polymer cleaning may, for example, be performed as
described by the method of FIGS. 1A-1C and 2, and/or the reactive
radicals may, for example, be generated using the process tools of
FIGS. 3, 4A, and 4B.
As illustrated by the cross-sectional view 500 of FIG. 5, a hard
mask layer 502 is formed over a semiconductor substrate 504. The
hard mask layer 502 may, for example, be formed of silicon dioxide
or silicon nitride, and/or the semiconductor substrate 504 may be,
for example, a silicon substrate (e.g., a bulk monocrystalline
silicon substrate), a germanium substrate, or a group III-V
substrate. In some embodiments, the process for forming the hard
mask layer 502 comprises depositing or otherwise growing the hard
mask layer 502 over the semiconductor substrate 504. For example,
the hard mask layer 502 may be grown by thermal oxidation, or
deposited by chemical or physical vapor deposition.
As illustrated by the cross-sectional view 600 of FIG. 6, a first
etch is performed into the hard mask layer 502 to pattern the hard
mask layer 502 with a fin pattern for the finFET. The fin pattern
may, for example, comprise one or more elongated features extending
laterally in parallel. In some embodiments, the process for
patterning the hard mask layer 502 comprises applying etchants 602
to the hard mask layer 502, while a first photoresist layer 604
lithographically patterned with the fin pattern is in place.
Further, in some embodiments, the process comprises removing or
otherwise stripping the first photoresist layer 604. The first
photoresist layer 604 may, for example, be removed or otherwise
stripped using the method of FIGS. 1A-C and 2 and/or using one of
the process tools of FIGS. 3, 4A, and 4B.
As illustrated by the cross-sectional view 700 of FIG. 7, a second
etch is performed into the semiconductor substrate 504 with the
hard mask layer 502 in place. The second etch results in one or
more fins 702 protruding upward from a base 704 of the
semiconductor substrate 504. Further, the second etch results in a
first polymer by-product layer 706 lining the semiconductor
substrate 504. The first polymer by-product layer 706 may be, for
example, fluorocarbon polymer or residue from dry etching gases.
Further, while the first polymer by-product layer 706 is shown
conformally lining the fin(s) 702 for ease of illustration, the
first polymer by-product layer 706 may, for example, have
length-wise discontinuities and/or non-uniformities in thickness.
In some embodiments, the process for performing the second etch
comprises applying an etchant 708 to the semiconductor substrate
504. The etchant 708 may, for example, be applied according to a
dry or plasma etch process and/or using, for example, a process gas
comprising carbon and fluoride, such as carbon tetrafluoride (e.g.,
CF.sub.4).
As illustrated by the perspective view 800 of FIG. 8, the fin(s)
702 resulting from the second etch extend laterally in
parallel.
As illustrated by the cross-sectional view 900 of FIG. 9, the first
polymer by-product layer 706 (see, e.g., FIGS. 7 and 8) is removed.
In some embodiments, the removal process comprises, or is otherwise
performed according to, the method of FIGS. 1A-C and 2. For
example, the removal process may comprise applying a fluid 106 with
reactive radicals 108, such as hydroxyl radicals, to the first
polymer by-product layer 706. Further, in some embodiments, the
removal process is performed using one of the process tools of
FIGS. 3, 4A, and 4B.
As illustrated by the cross-sectional view 1000 of FIG. 10, in some
embodiments, a third etch is performed into the hard mask layer 502
(see, e.g., FIG. 9) to remove the hard mask layer 502. In some
embodiments, the process for performing the third etch comprises
applying an etchant 1002 that is selective of the hard mask layer
502 to the hard mask layer 502. Further, in some embodiments, the
process comprises removing etch residue using the method of FIGS.
1A-C and 2, and/or using one of the process tools of FIGS. 3, 4A,
and 4B.
As illustrated by the cross-sectional view 1100 of FIG. 11, a first
dielectric layer 1102 is formed over the semiconductor substrate
504 and with an upper or top surface that is planar. The first
dielectric layer 1102 may, for example, be formed as silicon
dioxide, a low .kappa. dielectric (i.e., a dielectric with a
dielectric constant .kappa. less than about 3.9), or
phosphosilicate glass (PSG). In some embodiments, the process for
forming the first dielectric layer 1102 comprises depositing or
otherwise growing the first dielectric layer 1102 over the
semiconductor substrate 504. For example, the first dielectric
layer 1102 may be grown by thermal oxidation or deposited by vapor
deposition. Further, in some embodiments, the process comprises
performing a planarization into the upper or top surface of the
first dielectric layer 1102. The planarization may, for example, be
performed by a chemical mechanical polish (CMP).
As illustrated by the cross-sectional view 1200 of FIG. 12, a
fourth etch is performed into the first dielectric layer 1102 to
recess the upper or top surface of the first dielectric layer 1102
to below an upper or top surface of the fin(s) 702. In some
embodiments, the process for performing the fourth etch comprises
applying an etchant 1202 selective of the first dielectric layer
1102 to the first dielectric layer 1102 until the first dielectric
layer 1102 is sufficiently etched back. Further, in some
embodiments, the process comprises removing etch residue using the
method of FIGS. 1A-C and 2, and/or using one of the process tools
of FIGS. 3, 4A, and 4B.
As illustrated by the cross-sectional view 1300 of FIG. 13, a
second photoresist layer 1302 is formed masking a gate region of
the finFET. In some embodiments, the process for forming the second
photoresist layer 1302 comprises depositing the second photoresist
layer 1302 and subsequently patterning the second photoresist layer
1302 using lithography. The second photoresist layer 1302 may, for
example, be deposited by spin coating.
As illustrated by the perspective view 1400 of FIG. 14, the second
photoresist layer 1302 straddles the fin(s) 702 and extends
laterally in a direction orthogonal to a length of the fin(s) 702.
Further, the second photoresist layer 1302 is laterally spaced from
ends of the fin(s) 702, along the length of the fin(s) 702.
As illustrated by the cross-sectional view 1500 of FIG. 15, ions
1502 are implanted into regions of the fin(s) 702 that are unmasked
by the second photoresist layer 1302 to form source/drain regions
1602 (see, e.g., FIG. 16) in the fin(s) 702. Further, the ion
implantation forms a second polymer by-product layer 1504 (e.g., a
crust) along an outer surface of the second photoresist layer
1302.
As illustrated by the perspective view 1600 of FIG. 16, the
source/drain regions 1602 are formed laterally spaced along the
length of the fin(s) 702, on opposite sides of the second polymer
by-product layer 1504.
As illustrated by the cross-sectional view 1700 of FIG. 17, the
second photoresist layer 1302 (see, e.g., FIG. 15) and the second
polymer by-product layer 1504 (see, e.g., FIG. 16) are removed. In
some embodiments, the removal process comprises, or is otherwise
performed according to, the method of FIGS. 1A-C and 2. For
example, the removal process may comprise applying a fluid 106 with
reactive radicals 108 to the second photoresist layer 1302 and the
second polymer by-product layer 1504. Further, in some embodiments,
the removal process is performed using one of the process tools of
FIGS. 3, 4A, and 4B.
As illustrated by the perspective view 1800 of FIG. 18, the
source/drain regions 1602 are arranged on ends of the fin(s) 702
and laterally spaced by the gate region previously masked by the
second photoresist layer 1302 (see, e.g., FIG. 15).
As illustrated by the cross-sectional view 1900 of FIG. 19, a
second dielectric layer 1902 and a conductive layer 1904 are formed
covering the fin(s) 702. Further, the conductive layer 1904 is
formed over the second dielectric layer 1902 and with an upper or
top surface that is planar. The second dielectric layer 1902 may,
for example, be formed of silicon dioxide, and/or the conductive
layer 1904 may, for example, be formed of doped polysilicon or
metal. In some embodiments, the process for forming the second
dielectric layer 1902 and the conductive layer 1904 comprises
sequentially depositing and/or growing the second dielectric layer
1902 and the conductive layer 1904. The second dielectric layer
1902 and/or the conductive layer 1904 may, for example, be
deposited or otherwise grown conformally and/or using thermal
oxidation or vapor deposition. Further, in some embodiments, the
process comprises performing a planarization into the upper or top
surface of the conductive layer 1904.
As illustrated by the perspective view 2000 of FIG. 20, the second
dielectric layer 1902 and the conductive layer 1904 cover the
source/drain regions 1602 and the gate region previously masked by
the second photoresist layer 1302 (see, e.g., FIG. 15).
As illustrated by the cross-sectional view 2100 of FIG. 21, a fifth
etch is performed into the second dielectric layer 1902 (see, e.g.,
FIG. 20) and the conductive layer 1904 (see, e.g., FIG. 20) to form
a gate electrode 1904' straddling the fin(s) 702 and electrically
insulated from the fin(s) 702 by a gate dielectric layer 1902'. In
some embodiments, the process for forming the gate electrode 1904'
and the gate dielectric layer 1902' comprises applying etchants
2102 to the conductive layer 1904 and the second dielectric layer
1902, while a third photoresist layer 2104 lithographically
patterned with a gate pattern is in place. Further, in some
embodiments, the process comprises removing or otherwise stripping
the third photoresist layer 2104 using the method of FIGS. 1A-C and
2, and/or using one of the process tools of FIGS. 3, 4A, and
4B.
As illustrated by the perspective view 2200 of FIG. 22, the gate
dielectric layer 1902' and the gate electrode 1904' are formed
laterally between the source/drain regions 1602, thereby defining a
channel region along the length of the fin(s) 702.
With reference to FIG. 23, a flowchart 2300 of some embodiments of
the method of FIGS. 5-22 is provided.
At 2302, a hard mask layer with a fin pattern is formed over a
semiconductor substrate. See, for example, FIGS. 5 and 6.
At 2304, a first etch is performed into the semiconductor substrate
with the hard mask layer in place, such that a fin is formed
according to the fin pattern and a first polymer by-product layer
is formed lining the fin. See, for example, FIGS. 7 and 8.
At 2306, reactive radicals, such as hydroxyl radicals, are applied
to the first polymer by-product layer to remove the first polymer
by-product layer. See, for example, FIG. 9.
At 2308, a second etch is performed into the hard mask layer to
remove the hard mask layer. See, for example, FIG. 10.
At 2310, a first dielectric layer is formed laterally surrounding
the fin with an upper or top surface recessed below that of the
fin. See, for example, FIGS. 11 and 12.
At 2312, a photoresist layer is formed covering a gate region of
the fin. See, for example, FIGS. 13 and 14.
At 2314, ion implantation is performed into regions of the fin
unmasked by the photoresist layer, such that source/drain regions
are formed in the fin and a second polymer by-product layer is
formed on a surface of the photoresist layer. See, for example,
FIGS. 15 and 16.
At 2316, reactive radicals, such as hydroxyl radicals, are applied
to the second polymer by-product layer and the photoresist layer to
remove the second polymer by-product layer and the photoresist
layer. See, for example, FIGS. 17 and 18.
At 2318, a gate electrode is formed over the gate region of the
fin. See, for example, FIGS. 19-22.
While the method described by the flowchart 2300 is illustrated and
described herein as a series of acts or events, it will be
appreciated that the illustrated ordering of such acts or events
are not to be interpreted in a limiting sense. For example, some
acts may occur in different orders and/or concurrently with other
acts or events apart from those illustrated and/or described
herein. Further, not all illustrated acts may be required to
implement one or more aspects or embodiments of the description
herein, and one or more of the acts depicted herein may be carried
out in one or more separate acts and/or phases.
Thus, as can be appreciated from above, the present disclosure
provides a first method for removing polymer. An aqueous solution
is applied to a semiconductor workpiece with polymer arranged
thereon. The aqueous solution comprises an energy receiver
configured to generate hydroxyl radicals in response to energy.
Energy is applied to the aqueous solution to generate the hydroxyl
radicals in the aqueous solution and to remove the polymer.
In other embodiments, the present disclosure provides a process
tool for removing polymer. A chemical delivery device is configured
to apply an aqueous solution with an energy receiver to a
semiconductor workpiece. The energy receiver is configured to
generate hydroxyl radicals in response to energy. An energy input
device is configured to apply energy to the energy receiver, while
the chemical delivery device applies the aqueous solution to the
semiconductor workpiece, to generate the hydroxyl radicals.
In yet other embodiments, the present disclosure provides a second
method for removing polymer. A semiconductor manufacturing process
is performed to form polymer on a semiconductor workpiece. A fluid
with hydroxyl radicals is generated from ozonated deionized water
or hydrogen peroxide. The fluid is applied to the semiconductor
workpiece to remove the polymer from the semiconductor
workpiece.
The foregoing outlines features of several embodiments so that
those skilled in the art may better understand the aspects of the
present disclosure. Those skilled in the art should appreciate that
they may readily use the present disclosure as a basis for
designing or modifying other processes and structures for carrying
out the same purposes and/or achieving the same advantages of the
embodiments introduced herein. Those skilled in the art should also
realize that such equivalent constructions do not depart from the
spirit and scope of the present disclosure, and that they may make
various changes, substitutions, and alterations herein without
departing from the spirit and scope of the present disclosure.
* * * * *